What is Graves' disease?

Graves' disease is an autoimmune disease that affects the thyroid. The thyroid is a small gland in the front of the neck. It makes hormones called T3 and T4 that regulate how the body uses energy. Thyroid hormone levels are controlled by the pituitary, which is a pea-sized gland in the brain. It makes thyroid stimulating hormone (TSH), which triggers the thyroid to make thyroid hormone.

With Graves' disease, the immune system makes antibodies that act like TSH, causing the thyroid to make more thyroid hormone than your body needs. This is called an overactive thyroid or hyperthyroidism. An overactive thyroid causes every function of the body to speed up, such as heart rate and the rate your body turns food into energy. Graves' disease is one cause of overactive thyroid. It is closely related to Hashimoto's disease, another autoimmune disease affecting the thyroid.

Unlike other causes of an overactive thyroid, Graves' disease also can cause:

Eye changes. For some people with Graves' disease, the tissue behind the eyes becomes inflamed and swells. This can cause bulging or discomfort in one or both eyes. Sometimes it affects vision. Eye symptoms can occur before, at the same time, or after other symptoms of Graves' disease begin. It may rarely occur in people with normal thyroid function. We do not know why these eye problems occur. They are more common in people who smoke, andsmoking makes eye symptoms worse. Eye problems often get better without treatment.

Reddening and thickening of the skin, often on the shins and tops of the feet. This rare skin problem is not serious and is usually painless. Most people with this skin problem also have eye problems from Graves' disease.

Symptoms of Graves' disease can occur slowly or very suddenly and are sometimes confused with other health problems. Some people with Graves' disease do not have any symptoms.